1) Download Pacifist
http://www.versiontracker.com/dyn/moreinfo/macosx/12743
2) Download airport extreme update 2007-002
3) Download 10.4.9 combo update
4) Go to /system/library/extensions and copy appleairport.kext and appleairport2.kext to a backup location just to be safe and then delete them from the extensions folder.
5) Also in the extensions folder you'll find IO80211Family.kext and copy it to backup folder and then delete it.
6) Mount airport extreme update dmg and then open Pacifist.
7) In Pacifist click on "Open Package" and select the airport extreme update package.
8) In Pacifist you will now see all the files that are in the package. Find system and expand it's tree by clicking on the triangle. then expand library and then extensions. You will now see the IO80211Family.kext file. Click once on it so it's highlighted and then click "Install".
9) When it's done copying files expand coreservices and then menu extras. Highlight "Airport Menu" and click install.
10) When it's done copying close the window in Pacifist for the airport update package.
11) Now mount the 10.4.9 combo update dmg and click "Open Package" in Pacifist and select the 10.4.9 combo package.
12) Again find the system folder and expand it and then expand the libray and extensions folders.
13) In the extensions folder you'll see a bunch of files. Look for appleairport.kext and highlight it. Click "Install".
14) when it's done copying you should see the appleairport2.kext. Highlight it and click "install".
15) when Pacifist is done copying reboot your Macbook.
16) Once booted try your internet and then jump up and down shouting